什么情况下，oracle rac会发生交叉归档

cntoen

什么情况下，oracle rac会发生交叉归档，交叉归档示例如下？
SQL> select name,THREAD#,ARCHIVAL_THREAD# from v$archived_log a where a.THREAD#!=a.ARCHIVAL_THREAD# and rownum<=5;
NAME                                                            THREAD# ARCHIVAL_THREAD#
------------------------------------------------------------ ---------- ----------------
/home/oracle/archvelog/raw10g/2_1382_751300003.dbf                    2                1
/home/oracle/archvelog/raw10g/2_1383_751300003.dbf                    2                1
/home/oracle/archvelog/raw10g/1_1483_751300003.dbf                    1                2
/home/oracle/archvelog/raw10g/1_1484_751300003.dbf                    1                2
/home/oracle/archvelog/raw10g/2_1384_751300003.dbf                    2                1

Maclean Liu(刘相兵

ARCHIVAL_THREAD#     NUMBER     Redo thread number of the instance that performed the archival operation. This column differs from the THREAD# column only when a closed thread is archived by another instance.

http://docs.oracle.com/cd/E18283_01/server.112/e17110/dynviews_1016.htm

仅当 redo 相关的thread close时 其他实例会帮助归档 该thread上的 在线日志 online redo logfile  "交叉归档"

造成thread close的 可能性很多 ，例如实例正常关闭 或者abort

Shutting down archive processes
Archiving is disabled
Wed Jan 18 23:31:27 2012
ARCH shutting down
ARC0: Archival stopped
Wed Jan 18 23:31:27 2012
ARCH shutting down
ARC1: Archival stopped
Wed Jan 18 23:31:27 2012
ARCH shutting down
ARC3: Archival stopped
Wed Jan 18 23:31:27 2012
ARCH shutting down
ARC2: Archival stopped

Thread 2 closed at log sequence 146

Successful close of redo thread 2
Wed Jan 18 23:31:28 2012
NOTE: Deferred communication with ASM instance
NOTE: deferred map free for map id 13
Completed: ALTER DATABASE CLOSE NORMAL
ALTER DATABASE DISMOUNT
Shutting down archive processes
Archiving is disabled
Wed Jan 18 23:31:32 2012
NOTE: Deferred communication with ASM instance
NOTE: deferred map free for map id 2
Completed: ALTER DATABASE DISMOUNT
Wed Jan 18 23:31:38 2012
SUCCESS: diskgroup DATA was dismounted
NOTE: Database dismounted; ASMB process exiting
Stopping background process RBAL
Stopping background process MARK